A tissue processor automatically performs fixation, dehydration, cleaning, and paraffin impregnation of tissue samples (e.g., liver tissue, breast tissue, prostate tissue, etc.). At least two types of tissue processors exist, namely, chamber processors and station processors. A station-type processor includes a plurality of stations for processing the tissue samples, which are contained within individual cassettes. An example of a tissue cassette is disclosed in U.S. Pat. No. 4,421,246 to Schultz, which is incorporated herein by reference. The tissue cassettes are loaded into a single basket and taken from one station to the next station. In a chamber processor, tissue cassettes are loaded in a single enclosed chamber of the processor. The tissue cassettes remain stationary during processing in a fully enclosed retort while processing reagents and molten paraffin are moved to and from the chamber in a programmed sequence.
In both types of processors, all samples are immersed in a large reagent pool and cross-contamination of small tissue fragments may occur. Cross-contamination of the samples can skew the results of the tissue analysis. In view of the foregoing, there is a need to further refine tissue processors in the interests of reducing or eliminating cross contamination of tissue samples.